1. Field of the Invention
The present invention relates to a camera body structure for single lens reflex cameras, and more particularly pertains to such camera body structure which employs a unitized shutter block that is preassembled in a unit or block before it is coupled with the remaining parts of the camera body.
2. Description of the Prior Arts
The unitized shutter block, in which shutter blades and driving mechanism therefor are mounted on a base plate to be assembled in a camera as a unit or block, has recently been adopted in many single lens reflex cameras. This is because such unitized shutter device can be dealt with as a block upon assemblage of cameras and may be adjusted or calibrated, for example, with respect to its operation, relative position of its particular parts, shutter speed, etc., before the device is associated in a camera body so that the single lens reflex cameras employing such unitized shutter block are suitable for mass production with the adjusting process for such cameras being facilitated.
In the conventional single lens reflex cameras employing the unitized shutter device, a front plate which has a mount for the interchangeable lens and to which the mirror box including the reflex mirror and diaphragm driving mechanism has been fixed, is attached to the main camera body, after the shutter block is mounted on a main camera body including a film receptacle, film driving mechanism and shutter cocking mechanism. Accordingly, due to accumulation of errors occuring, upon coupling, at relative positions between the shutter block and the main camera body, between the front plate and the main camera body, and between the mirror box and the front plate, the relative position of the mirror box to the shutter block is liable to deviate from the desired position, resulting in imperfect interconnection between the shutter driving mechanism in the unitized shutter block, and the diaphragm and the mirror driving mechanism on the mirror box.
It may be possible in such a case to adjust relating mechanisms for perfecting the interconnection. With the conventional single lens reflex cameras, operation and examination, as to interconnections and operations, of their shutter, reflex mirror and diaphragm driving mechanisms are available only after the shutter block, mirror box and front plate are all assembled in a camera body. However, the examination and adjustment of their mechanism are in fact difficult in the conventional cameras, because portions or parts to be adjusted are likely to be blocked by the other parts or mechanism in the assembled condition. Therefore, in such conventional cameras, safety tolerance and space are provided between the shutter driving mechanism and the diaphragm and mirror driving mechanism, taking into account the accumulated error, so that the difficult adjustment may not be required. As a result, interconnected members are necessarily required to move greatly and the drive force therefor will also be large, thereby increasing the force for shutter cocking and noise upon the operation of the members, as well as shortening the lifetime of the members. Additionally, the safety space itself will be one of the factors against providing compactness of the camera body.